| Useful lives or depreciation rates, property, plant and equipment | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Concept not required as a result of 2018 annual improvements | en | http://www.xbrl.org/2009/role/deprecatedLabel | http://www.xbrl.org/2003/role/link |
| 2019-01-01 | en | http://www.xbrl.org/2009/role/deprecatedDateLabel | http://www.xbrl.org/2003/role/link |
| The useful lives or depreciation rates used for property, plant and equipment. [Refer: Property, plant and equipment] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |